soc/intel/xeon_sp/skx: Use Kconfig symbol

Use Kconfig symbol CPU_BCLK_MHZ as done on CPX.

Reduced code differences between SKX and CPX and will allow to
merge the codebase into one.

Change-Id: I8a0a51d4280e4370e0e8695f8b9d8f2ed943d9e4
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/84847
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Shuo Liu <shuo.liu@intel.com>

src/soc/intel/xeon_sp/skx/Kconfig

@@ -25,6 +25,10 @@ config MAX_CPUS
 	int
 	default 80
 
+config CPU_BCLK_MHZ
+	int
+	default 100
+
 config PCR_BASE_ADDRESS
 	hex
 	default 0xfd000000

src/soc/intel/xeon_sp/skx/cpu.c

@@ -165,8 +165,6 @@ static const struct cpu_driver driver __cpu_driver = {
 	.id_table = cpu_table,
 };
 
-#define CPU_BCLK 100
-
 static void set_max_turbo_freq(void)
 {
 	msr_t msr, perf_ctl;
@@ -190,7 +188,7 @@ static void set_max_turbo_freq(void)
 	wrmsr(IA32_PERF_CTL, perf_ctl);
 
 	printk(BIOS_DEBUG, "cpu: frequency set to %d\n",
-	       ((perf_ctl.lo >> 8) & 0xff) * CPU_BCLK);
+	       ((perf_ctl.lo >> 8) & 0xff) * CONFIG_CPU_BCLK_MHZ);
 	FUNC_EXIT();
 }